1. Field
The following description relates to an image sensor, and more particularly, to a pixel of a multi-stacked complementary metal-oxide semiconductor (CMOS) image sensor and a method for manufacturing the same.
2. Description of the Related Art
As a resolution of a complementary metal-oxide semiconductor (CMOS) image sensor of a silicon photodiode is increased, a pixel size of an image sensor is reduced.
As a pixel size of an image sensor is reduced, a light-receiving area of a photodiode in the pixel is decreased. As a result, a sensitivity of the image sensor may deteriorate. Also, if the pixel size is reduced and a thickness of the pixel remains the same size, an aspect ratio of the pixel may increase, crosstalk between adjacent pixels may increase, and a signal-to-noise ratio (SNR) may decrease. Accordingly, an image quality of the image sensor may deteriorate.
The aforementioned problems may be improved by stacking red (R), green (G), and blue (B) layers in the pixel and dividing a photodiode of each of the R, G, and B layers by an oxide layer.
After the pixel having a multi-stacked structure is formed, a via hole should be formed to send a signal of each of the R, G, and B layers to a CMOS readout integrated circuit (ROIC). However, this operation may be difficult and may cause complexity in the process.
Typically, the via hole in a pixel structure is formed by etching a plurality of material layers. The plurality of layers typically include an organic semiconductor layer, an insulating layer, a transparent electrode layer, and the like. The etching may be performed on each of the plurality of material layers via a wet etching process or via a photolithography process using a photoresist.
When the etching is performed on each of the plurality of material layers via the etching process, an organic layer in the pixel may be damaged due to a solution that is used during the etching.
Also, when the via hole is formed in the plurality of material layers via the etching process, a conductive material that fills the via hole may contact an electrode of each of the plurality of material layers in the pixel such that a short may occur. Thus, an image sensor manufacturing process may be further complicated by adding a process of depositing an insulating layer in the via hole in order to prevent the short.